The present invention relates to a body cavity inserting instrument, and more particularly, to a body cavity inserting instrument, such as an instrument for taking a cellular tissue in a cavity of a living body, which has a bending mechanism whose distal treatment portion is bendable to adjust its direction.
There is known a bending mechanism in an instrument for medical treatment of the kind as described above as shown in Japanese Utility Model Publication Sho 56 - 10329.
Specifically, this bending mechanism, as shown in FIG. 9, includes a loosely wound coil part 10a which is properly spaced between coil elements and which is disposed at the front end of a flexible tubular member 10 formed of closely wound coils and a member 11 for adjusting expansion and contraction of the loosely wound coil part which is made of a beltlike elastic plate and which is disposed within the coil part 10a in the longitudinal direction of the tubular member towards one side of the inner peripheral surface of the coil part 10a, the opposite ends of the member 11 being fixed to the inner peripheral surface of the coil part 10a. A fixing member 14 is fixed to the front end of the coil part 10a. The base of a brush 12 and the front end of an operating wire 13 are fixed to the fixing member 14. By pulling the operating wire 13 passing through the tubular member 10 to the proximal side of an instrument, a compressive force is applied to the tubular member 10 to reduce the space between coil elements of the coil part 10a on the side where the adjusting member 11 is not fixed. As a result, the coil part 10a bends drawing an arc on the side where the adjusting member 11 lies and thereby the brush 12 is bent to a direction shown by an arrow.
With a conventional bending mechanism as described above, however, only the opposite side of the coil part 10a where the adjusting member 11 is not fixed is reduced as described above and the side where the member 11 is fixed is kept stationary without expansion and contraction. Consequently, a bending angle is so small as to be insufficient in an operation of taking a tissue.